1. Field of the Invention
The present invention relates to observation devices, observation systems, control devices, and control programs, and is suitable particularly for a biotechnological observation using a microscope.
2. Description of Related Art
Observation devices using a microscope are used in the fields of medicine, biology and the like in order to accurately capture a minute object to be observed such as a cell or microorganism (This includes bacteria, virus and the like, and is hereinafter referred to as a cell or the like). This observation device comprises a stage on which a fluid vessel or the like containing therein the object to be observed is placed, a driving part electrically moving the stage, and an observing part observing the object to be observed (observation object). In this observation device, the observation object is automatically moved to change the observed area. In the case where the observation object is periodically observed, it is required that the stage is stopped at the same position every time the stage is moved.
In the driving part moving the stage on which the observation object is placed by using an electric motor or the like, a mechanism interposed between a motor part and the stage includes a mechanical operation part such as a gear, pulley and the like. It is known that a backlash occurs in the mechanical operation part due to play and rattling between the gears, or in the gear itself or the pulley. Therefore, in the case where the mechanism is not a mechanism which is provided with a position sensor and performs feedback control using position information regarding the stage from the position sensor, for example, in the case where the position of the stage is controlled based on the number of rotations of the electric motor or the like, the actual position of the stage cannot necessarily be obtained from the number of rotations of the electric motor due to generation of a lost motion caused by the backlash. Therefore, in the control using the number of rotations of the electric motor, an error (hereinafter referred to simply as a movement error or a position error) occurs in an actual stop position of the stage every time the stage is driven. This position error due to the lost motion caused by the backlash has an unignorable influence in a field in which the observation object is minute.
In order to solve the backlash due to the influence of the play between the gears, it has been suggested a technique of storing information of a rotation direction of the gear at the time of stopping the gear to control the movement of the stage using the information so that the rotation direction at the time of stopping the gear is always the same.
In the mechanical operation part such as the gear, pulley and the like described above, (i) there is a lost motion due to stiffness, mass or the like as well as the lost motion due to the backlash described above. In other words, the lost motion occurs due to generation of twisting, distortion, or slip of the gear, a rotation axis part of the pulley, a tooth part of the gear, a surface part of the pulley or the like forming the mechanical operation part depending on the stiffness, mass or the like of materials of these parts. Also, regarding a chain or belt forming the mechanical operation part, the lost motion occurs due to the generation of expansion and contraction, twisting, or distortion depending on the stiffness, mass or the like of materials of the chain or belt. The above mentioned lost motion occurs because a part of the torque of a sender is absorbed due to the twisting, distortion, or the like described above, and the absorbed torque is not transmitted to a receiver. The lost motion depending on the stiffness, mass or the like causes the position error of the stage.
Additionally, the position error of the stage occurs not only due to the lost motion depending on the stiffness, mass or the like, but also due to moving acceleration or the like depending on the stiffness, mass or the like. That is, (ii) since moving velocity, moving acceleration or the like of the observation object (stage) at the time of performing a control for stopping the stage is not uniform most of the times, the state of the twisting, distortion, or the like of the axis part or the tooth part of the gear varies each time the stage is stopped, resulting in the position error such that the stop position of the stage is different every time the stage is moved.
The movement error and the position error of the stage due to the stiffness, mass or the like described above in (i) and (ii) are hereinafter referred to simply as a “position error due to stiffness, mass or the like”.
The conventional art discloses solutions to the problem of only the lost motion due to the backlash such as play, rattling or the like between the gears, and cannot handle the position error due to the stiffness, mass or the like described above. In other words, although, in the conventional art, the information of the stop position and the movement direction of the stage is stored in order to solve the problem of the lost motion due to the backlash, the conventional art does not disclose storing the velocity and acceleration in a stage driving. Accordingly, the velocity and acceleration in the stage driving are not considered in the conventional art, and it is not possible to handle a position error due to stiffness, mass or the like described above only by considering the position and the movement direction of the stage without considering the velocity and acceleration of the stage driving.